WDM multiplexing/de-multiplexing system and the manufacturing method thereof

ABSTRACT

A WDM multiplexing/demultiplexing system includes a de-multiplexer configured to separate and guide light beams from an incident ray having a plurality of wavelengths to corresponding lenses on an optical device, a multiplexer configured to guide light beams from optical transmitters having various wavelengths through the corresponding lenses on the optical device and combine the light beams, a lens array including the corresponding lenses to receive and/or transmit the light beams from or to the de-multiplexer and multiplexer, and a light beam collimator configured to function with the multiplexer and de-multiplexer. The light beams received or transmitted by the light beam collimator and the light beams transmitted or received from or to the multiplexer and de-multiplexer are collinear. The light beam collimator and multiplexer/de-multiplexer can be easily positioned to predetermined or designed positions, thereby providing light beams output through the lenses in a plastic optical device. The WDM system advantageously reduces optical signal loss, while increasing the assembly yield.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Chinese Patent Application No.201210402718.4, filed on Oct. 22, 2012, incorporated herein by referenceas if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to a photoelectric conversion component infiber optic data communications and telecommunications. In particular,embodiments of the present invention pertain to a wavelength divisionmultiplexing (WDM; e.g., a coarse wavelength division multiplexing[CWDM]/de-multiplexing system and a manufacturing method thereof.

DISCUSSION OF THE BACKGROUND

Coarse wavelength division multiplexing (CWDM) is a technology thatmultiplexes multiple optical signals on a single optical fiber strand byusing different wavelengths of laser light to carry different signals.There are two conventional CWDM systems. One conventional CWDM system isformed by single wavelength optical communication modules using anexternal multiplexer/demultiplexer (MUX/DEMUX). The other conventionalCWDM system realizes zigzag optical path actions of the MUX/DEMUX usinginjection molded plastic optical devices and thin film filters. Suchconventional techniques provide low cost and low power consumption.However, there are some issues with these conventional techniques.

FIG. 1 is a diagram showing a conventional MUX/DEMUX system 100 having a“zigzag” optical path. In MUX/DEMUX systems 100 having the zigzagoptical path, light from an optical source providing multiplewavelengths enters into an optical input port 102. Subsequently, thewavelengths are separated to each output port in optical module 101 bywavelength to realize de-multiplexing. Because the de-multiplexingprocess is reversible, four or more light beams having differentwavelengths may be combined into one output light beam in themultiplexing process.

FIG. 2 is a diagram showing a conventional MUX/DEMUX component 200. FIG.3 is a diagram showing the internal optical path 215 of the component200 of FIG. 2. Generally, the optical module 201 implementsmultiplexing/de-multiplexing using the zigzag optical path 215. Theconventional MUX/DEMUX system 200 may realize a smaller size, lowercost, and easier insertion and/or extraction of the optical fiber incomparison with system 100 of FIG. 1.

FIG. 4 shows a layout of a printed circuit board (PCB) 209 having anelectrical circuit 211 adapted for relatively long conventional plasticoptical devices. Typically, relatively long electrical circuitsnegatively affect the transmission performance of high speed digitalsignals.

One issue with the conventional MUX/DEMUX system(s) shown in FIGS. 2 and3 is that a lens array having an arrangement parallel with incidentlight can affect the transmission performance of high speed digitalelectrical signals at the back-end of a fiber-optic communicationdevice. Also, during assembly of a plastic optical communication device,the accumulated tolerances of positioning of various devices such as thecollimator and the MUX/DEMUX system can prevent collimated light beamsfrom the collimator being aligned properly with lenses in the plasticoptical device. As a result, conventional MUX/DEMUX systems may have arelatively low yield.

This “Discussion of the Background” section is provided for backgroundinformation only. The statements in this “Discussion of the Background”are not an admission that the subject matter disclosed in this“Discussion of the Background” section constitutes prior art to thepresent disclosure, and no part of this “Discussion of the Background”section may be used as an admission that any part of this application,including this “Discussion of the Background” section, constitutes priorart to the present disclosure.

SUMMARY OF THE INVENTION

Embodiments of the present invention are intended to provide a WDM(e.g., CWDM) multiplexing/de-multiplexing system and a manufacturingmethod thereof to overcome one or more of the issues with conventionalMUX/DEMUX systems.

The present invention provides a WDM (e.g., CWDM)multiplexing/de-multiplexing system, comprising (i) a de-multiplexerconfigured to separate and guide first light beams from an incident rayhaving a plurality of wavelengths to corresponding lenses on an opticaldevice, (ii) a multiplexer configured to combine and guide second lightbeams from a plurality of optical transmitters, each such second lightbeam having a unique wavelength that passes through a corresponding lenson the optical device, wherein the multiplexer and the de-multiplexertogether form a bi-directional optical subassembly (BOSA), (iii) anarray of the corresponding lenses, to receive the first light beams fromthe demultiplexer and transmit the second light beams to themultiplexer, and (iv) a light-beam collimator configured to function orwork with the multiplexer and de-multiplexer.

In various embodiments of the present invention, a light beam receivedor transmitted by the light-beam collimator and a light beam from or tothe multiplexer/de-multiplexer are collinear. In one such embodiment, atransimpedance amplifier (TIA) array on a printed circuit board (PCB)can have the shortest wiring length to connect with the electricalconnector on the PCB. Preferably, the lens array orientation isperpendicular to the light beam transmitted from or received by thelight-beam collimator.

Preferably, the multiplexer/de-multiplexer and the light-beam collimatorare on or in the same plastic optical device, which has a molded lensarray thereon. In an exemplary embodiment, the lens array is integratedinto the plastic optical device. Preferably, the plastic optical deviceis molded by injection molding.

In various embodiments, the lens array comprises at least two lenses. Inan exemplary embodiment of the present invention, the lens arraycomprises four lenses. Preferably, the lenses are equally spaced atfixed intervals (for example, 750 microns, but not limited to 750microns). The interval between the lenses may be based on the number oflenses and the actual demand.

In further embodiments, the lens array is accompanied by alignment holesin accordance with an applicable fiber patchcord (e.g., an optical fiberribbon and/or cable) specification. Corresponding fiber patchcords havealignment pins corresponding to the alignment holes. In an exemplaryembodiment, the fiber patchcord is a mechanical transfer (MT) fiberpatchcord. However, any multiple fiber patchcord using alignment pinsand alignment holes for passive alignment is within the spirit of thisinvention.

The present invention further provides a method of manufacturing the WDM(e.g., CWDM) multiplexing/de-multiplexing system, comprising: (i)matching the alignment pins on a fiber patchcord (e.g., an optical fiberribbon or cable) with the alignment holes in a plastic optical device,and using the fiber patchcord to connect the lens array in the plasticoptical device with one or more optical power meters (in one example,the number of fibers in the patchcord corresponds to the number oflenses in the lens array); (ii) positioning a multiplexer/de-multiplexerand a light-beam collimator in the plastic optical device; (iii)changing relative positions of the light-beam collimator and themultiplexer/de-multiplexer until each optical power meter detects astandard or predetermined optical output power level. Subsequently,fixing the light-beam collimator and the multiplexer/de-multiplexer onthe plastic optical device with UV adhesive to assemble (e.g., finishthe assembly process of) the plastic optical device, the light-beamcollimator, and the multiplexer/de-multiplexer.

The present invention further concerns an optical receiving device,comprising the WDM and/or CWDM multiplexing/de-multiplexing system, anoptical receiving portion, and an electrical circuit. The opticalreceiving portion is configured to function or work with the lens arrayin the WDM and/or CWDM multiplexing/dc-multiplexing system. The opticalreceiving portion comprises an optical detector array.

Furthermore, the present invention relates to an optical transmittingdevice, comprising the WDM and/or CWDM multiplexing/de-multiplexingsystem, an optical transmitting portion and an electrical circuit,wherein a light beam that is emitted from the optical transmittingportion is captured by the lens array of the WDM and/or CWDMmultiplexing/de-multiplexing system.

The present invention further relates to an opticaltransmitting-receiving device, comprising the WDM and/or CWDMmultiplexing/de-multiplexing system, an optical receiving portion, anoptical transmitting portion, and an electrical circuit. The opticaltransmitting-receiving device comprises the present WDM and/or CWDMmultiplexing/de-multiplexing system, wherein a light beam that isemitted from the optical transmitting portion is captured by a part ofthe lens array, and the light beam that is emitted from the other partof the lens array is received by the optical receiving portion.Preferably, the optical transmitting portion comprises a surfaceemitting laser array or an edge-emitting laser array, and the opticalreceiving portion comprises an optical detector array.

Conventional plastic optical devices do not have an alignment holesystem. As a result, the accumulated tolerance generated by positioningvarious devices can cause the collimated beam to not pass through thecorresponding lens of the lens array in the plastic optical deviceduring the assembly of the plastic optical device, the collimator, andthe MUX/DEMUX. Consequently, the conventional design may have arelatively low yield.

In the present invention, the plastic optical device has precisealignment holes in locations (e.g., sides) where the lens array ispositioned. Thus, active optical power monitoring is provided byconnecting the MT fiber patchcord to the optical power meters. In otherwords, the present invention advantageously enables positioning thelight-beam collimator and the multiplexer/de-multiplexer to fitpredetermined or designed positions. From a technical point of view,manufacturing lenses and alignment holes with precise positions andsizes is relatively mature technology and can be applied in thisinvention.

Relative to existing technologies, the present invention advantageously:

-   -   (i) enables the optical design to reduce the length of the        electrical transmission path of high speed digital signals on        the PCB;    -   (ii) provides an easier manufacturing process with the        introduction of the alignment holes on the plastic optical        device and an MT fiber patchcord;    -   (iii) reduces the optical power loss of the optical signal        caused by misalignment during assembly and increases the yield        by introducing precise alignment holes accompanying the plastic        lens array; and    -   (iv) provides active optical power monitoring by connecting the        MT fiber patchcord to the corresponding optical power meter,        thereby positioning the light-beam collimator and the        multiplexer/de-multiplexer to fit predetermined or designed        positions in the present plastic optical device.

Thus, the present invention provides a molded plastic optical devicewith a unique assembly procedure for a receiver (e.g., a 40 G/100 Greceiver) optical subassembly. In the present molded plastic opticaldevice, a mechanical transfer (MT) based guiding structure functions asthe detector array during the assembly process. With the help of the MTfiber patchcord, the light-beam collimator and the DEMUX can be alignedto a predetermined or designed position through the active alignmentmethod. This is a benefit from designing the MT-based guide or alignmentholes in the plastic optical device. Thus, a passive alignment methodthrough the alignment mechanism can be applied, and the MT-basedpatchcord may simulate the optical detector array for the activealignment of the zigzag type DEMUX and the light-beam collimator.

These and other advantages of the present invention will become readilyapparent from the detailed description of various embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a conventional multiplexer/de-multiplexer(MUX/DEMUX) system.

FIG. 2 is a diagram showing a conventional plastic molded MUX/DEMUXsystem.

FIG. 3 is a diagram showing an internal optical path of the MUX/DEMUX inFIG. 2.

FIG. 4 shows a layout of a printed circuit board (PCB) having anelectrical circuit (including traces) adapted for a conventional opticaldetector arrangement.

FIG. 5 is a diagram showing connections among various components, suchas the optical device, a light-beam collimator, and a MUX/DEMUX.

FIG. 6 is a perspective view showing alignment holes in an example ofthe present plastic optical device, aligned with the alignment pins on amechanical transfer (MT) fiber patchcord.

FIG. 7 is a drawing showing the setup and/or use of a MT-based fiberpatchcord to simulate the optical detector array and then measure theoptical power level of each DEMUXed wavelength by each individual powermeter through the MT-based fiber patchcord.

FIG. 8 is a side view showing the setup between the MT-based fiberpatchcord and a plastic optical device in accordance with the presentinvention.

FIG. 9 is a diagram showing the assembly of the plastic optical devicealigned with a PCB in accordance with the present invention.

FIG. 10 is an exemplary layout showing a PCB electrical circuit(including traces) adapted for the present plastic optical device.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of theinvention, examples of which are illustrated in the accompanyingdrawing(s). In order to achieve the objectives, technical solutions andadvantages of the present invention more clearly, further details of theinvention are described below with regard to the Figure(s). While theinvention will be described in conjunction with the followingembodiments, it will be understood that the descriptions are notintended to limit the invention to these embodiments. On the contrary,the invention is intended to cover alternatives, modifications andequivalents that may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description, numerous specific details are set forthin order to provide a thorough understanding of the present invention.However, it will be readily apparent to one skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components, andcircuits have not been described in detail so as not to unnecessarilyobscure aspects of the present invention. The embodiments described hereare only used to explain, rather than limit, the invention.

The technical proposal(s) of embodiments of the present invention willbe fully and clearly described in conjunction with the drawing. In thefollowing embodiments, it will be understood that the descriptions arenot intended to limit the invention to these embodiments. Based on thedescribed embodiments of the present invention, other embodiments can beobtained by one skilled in the art without creative contribution, andare in the scope of legal protection given to the present invention.

Furthermore, all characteristics, measures or processes disclosed inthis document, except characteristics and/or processes that are mutuallyexclusive, can be combined in any manner and in any combinationpossible. Any characteristic disclosed in the present specification,claims, Abstract and Figures can be replaced by other equivalentcharacteristics or characteristics with similar objectives, purposesand/or functions, unless specified otherwise. Each characteristic isgenerally only an embodiment of the invention disclosed herein.

As shown in FIGS. 5-10, the present WDM (e.g., CWDM system) 300comprises a plastic optical device 301, a collimator 302 connected tothe front end of the plastic optical device 301, a MUX/DEMUX 303 mountedon the plastic optical device 301, and a lens array 308 configured toreceive light from the MUX/DEMUX 303 and/or transmit light to theMUX/DEMUX 303. Light received or transmitted by the collimator 302 andlight from or to the MUX/DEMUX 303 are collinear.

Referring to FIGS. 6-7, the present WDM system and assembly process mayfurther comprise a mechanical transfer (MT) fiber patchcord or cable 304having two alignment pins 305, optical power meters 314 (FIG. 7)connected to the MT fiber patchcord 304 via an optical fiber 307, andtwo alignment holes 306 on the surface of the plastic optical device301. With alignment pins 305 aligned and/or matching with the alignmentholes 306, the MT fiber patchcord 304 is utilized to simulate theoptical detector array as an intermediate process during the assemblyamong the collimator, the plastic optical device, and the MUX/DEMUX.

Referring to FIGS. 8-9, injection molded plastic optical device 301functions as a base, holder, or frame for the MUX/DEMUX 303 and thecollimator 302. Light having various wavelengths transmitted from theDEMUX 303 can be guided to corresponding lenses in the lens array 308 inor on the plastic optical device 301, as shown in FIG. 9. The lens array308 comprises lenses that are spaced apart by, e.g., 750 microns. As aresult, the lens array 308 is compatible with the four optical detectors312, followed by the transimpedance amplifier (TIA) array 313, at theback end 315 of the plastic optical device 301, as shown in FIG. 10FIGS. 9-10. In such a configuration, the orientation of the opticaldetector array 312, the transimpedance amplifier (TIA) array 313, andthe electrical metal lines are substantially parallel at the back end316 of the optical device 301 PCB. This arrangement allows the outputfrom the TIA array 313, which are behind the optical detector array 312,to be transmitted to an electrical cable (e.g., connected to a hostdevice) on the PCB 309 at the back end 316 via relatively shortelectrical metal lines or traces 310.

Referring back to FIG. 4, which is an exemplary layout showing a PCB 209having an electrical circuit arrangement 211 adapted for conventionalplastic optical devices, the metal lines or traces in this electricalcircuit arrangement 211 are relatively long. As previously discussed,long electrical metal lines or traces negatively affect the transmissionperformance of high speed digital signals. Distortion due to longtransmission traces (such as in the layout in FIG. 4) when using opticaldetector array 212 accompanying with the TIA array 213 to convertoptical signals into high speed digital electrical signals may bereduced by implementing the layout and/or circuitry shown in FIG. 10.

Referring back to FIGS. 5-6, two alignment holes 306 that are compatibleor mated with the alignment pins 305 on the MT fiber patchcord or cable304 are applied to and/or formed in the plastic optical device 301. Bypositioning the two alignment pins 305 on the MT fiber patchcord 304into the two alignment holes 306 on the plastic optical device 301, a MTfiber ribbon formed from four single-mode or multi-mode fibers 307 maybe connected to four individual optical power meters 314, as shown inFIG. 7. The fiber 307 is connected with the optical power meter 314 tomonitor the optical power level during the assembly process. The fibers307 in the MT fiber patchcord 304 can passively align with the lensarray 308 on the plastic optical device 301 to receive light from theMUX/DEMUX 303 with the greatest coupling efficiency through the activealignment method.

In addition, in the WDM and/or CWDM system, the relative positions ofthe collimator 302 and the MUX/DEMUX 303 may be changed or adjusteduntil each optical power meter 314 detects a predetermined, specifiedand/or standardized optical output power level. Furthermore, to completethe assembly of the WDM and/or CWDM system, the collimator 302 andMUX/DEMUX 303 may be fixed to the plastic optical device 301 with a UVadhesive. First, the light-beam collimator 302 and the MUX/DEMUX 303 aremounted in adjustable locations on the device 301, then the optimallocations are determined using the optical power meter(s), and thelocations of 302 and 303 are secured using UV adhesive when the optimallocations are determined.

If there are no alignment holes in the WDM and/or CWDM system in theplastic optical device 301, the accumulated tolerances of positioningvarious devices in the WDM and/or CWDM system may prevent collimatedlight beams from the collimator 302 from properly passing through thelenses in plastic optical device 301 during the assembly of the plasticoptical device 301, the collimator 302, and the MUX/DEMUX 303. Thus,conventional WDM and/or CWDM systems may result in relatively lowyields. In the WDM and/or CWDM system of the present invention,positioning the pins 305 on the MT fiber patchcord to align or match upwith the alignment holes 306 in the plastic optical device 301 providesadequate alignment of the collimator 302 and the MUX/DEMUX 303 inpredetermined or designed positions. As a result, collimated light fromthe collimator 302 can be guided to the lens array 308 on the plasticoptical device 301, which advantageously reduces the energy loss of theoptical signal, thus increasing the yield.

The introduction of the alignment holes 306 on the plastic opticaldevice 301 can simplify the alignment process of the collimator 302 andthe MUX/DEMUX 303 through active alignment skill. Similarly, it can beused in manufacturing process of a transmitter optical subassembly(TOSA) and a bi-directional optical subassembly (BOSA). The opticalreceiving portion is the optical detector array 312, and the opticaltransmitting portion is a surface emitting laser array or edge-emittinglaser array (not shown).

The present WDM and/or CWDM multiplexing/de-multiplexing system employsthe MT fiber patchcord 304 with optical power meters 314 to align thecollimator 302, the WDM and/or CWDM MUX/DEMUX 303 to the predeterminedor designed positions on the optical device 301. Various embodiments ofWDM and/or CWDM systems with alignment pins aligning to the alignmentholes via precise molds and corresponding devices may be used and arewithin the scope of the present invention.

CONCLUSION/SUMMARY

Thus, the present invention provides a WDM multiplexing/de-multiplexingsystem (e.g., a CWDM multiplexing/de-multiplexing, system), andmanufacturing method thereof. The WDM and/or CWDMmultiplexing/de-multiplexing system comprises (i) a de-multiplexerconfigured to separate and guide light beams from an incident ray havinga plurality of wavelengths to corresponding lenses on the opticaldevice, (ii) a multiplexer configured to combine and guide light beamsfrom a plurality of optical transmitters, the light beams having aplurality of wavelengths and passing through the corresponding lenses onthe optical device, wherein the multiplexer and the de-multiplexertogether form a bi-directional optical subassembly (BOSA), (iii) a lensarray comprising the corresponding lenses to receive the light beamsfrom and transmit the light beams to the de-multiplexer and multiplexer,and (iv) a light-beam collimator configured to function or work with themultiplexer and de-multiplexer. A light beam received or transmitted bythe light-beam collimator and a light beam from or to themultiplexer/de-multiplexer are collinear. The light-beam collimator andthe multiplexer/de-multiplexer can be easily positioned to thepredetermined or designed positions through the introduction ofalignment holes in the plastic optical device, a MT-based patchcord withoptical power meters, and active alignment skill. With the alignmentholes in the plastic optical device, a patchcord with alignment pins canmatch up with the alignment holes to simulate the optical detector arrayin situ. As a result, the present WDM and/or CWDM system advantageouslyreduces optical signal loss and increases the assembly yield.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

What is claimed is:
 1. A WDM multiplexing/de-multiplexing system,comprising: a de-multiplexer configured to separate and guide firstlight beams from an incident ray having a plurality of wavelengths tocorresponding lenses on an optical device; a multiplexer configured tocombine and guide second light beams from a plurality of opticaltransmitters, the second light beams having a plurality of wavelengthsand passing through said corresponding lenses on said optical device,wherein said multiplexer and said de-multiplexer together form abi-directional optical subassembly (BOSA); a lens array comprising saidcorresponding lenses to receive said first light beams from saidde-multiplexer and transmit said second light beams to said multiplexer,wherein said lens array comprises four lenses in a row, oriented along adirection that is parallel with a back end of the optical device andperpendicular to said first and second light beams; alignment holesaccompanying or adjacent to said lens array; a light-beam collimatorconfigured to receive the second light beams directly from saidmultiplexer and provide the first light beams directly to saidde-multiplexer, wherein the second light beams received by thelight-beam collimator are collinear with the first light beams providedby the light-beam collimator; and a printed circuit board having aplurality of optical detectors oriented along the direction that isparallel with the back end of the optical device, a plurality oftransimpedance amplifiers oriented along a direction that is parallelwith the plurality of optical detectors, and a plurality of electricalmetal lines or traces thereon, the optical detectors receiving the firstlight beams from the lens array, the electrical metal lines or tracestransmitting an output from the transimpedance amplifiers to aninterface for an electrical cable or to a host device, wherein thetransimpedance amplifiers are physically located between the opticaldetectors and the interface.
 2. The system of claim 1, wherein saidoptical device comprises a plastic optical device having said lensarray, said multiplexer/de-multiplexer, and said light-beam collimatorthereon.
 3. The system of claim 2, wherein said lens array is integratedinto said plastic optical device.
 4. The system of claim 3, wherein saidlenses are spaced apart by equal intervals.
 5. The system of claim 2,wherein said plastic optical device comprises an injection moldedoptical device.
 6. The system of claim 2, wherein said alignment holesare between said lens array and a peripheral edge of said plasticoptical device that is perpendicular to the back end of the plasticoptical device.
 7. The system of claim 6, further comprising a fiberpatchcord or a cable having alignment pins corresponding to saidalignment holes.
 8. The system of claim 7, wherein said fiber patchcordor said cable comprises a mechanical transfer (MT) fiber patchcord orsaid cable.
 9. The system of claim 7, wherein said fiber patchcord orsaid cable comprises multiple fibers with alignment pins.
 10. A methodof manufacturing the WDM multiplexing/de-multiplexing system of claim 1,comprising: matching alignment pins on a multiple fiber opticalpatchcord with said alignment holes in a plastic optical devicecomprising the lens array, and using each fiber in the multiple fiberpatchcord to connect each lens of the lens array in said plastic opticaldevice with a corresponding optical power meter; positioning themultiplexer/de-multiplexer and the light-beam collimator in said plasticoptical device; and changing relative positions of said light-beamcollimator and said multiplexer/de-multiplexer until each optical powermeter detects a standard, specified or predetermined optical outputpower level.
 11. The method of claim 10, further comprising fixing saidlight-beam collimator and said multiplexer/de-multiplexer to saidplastic optical device with UV adhesive.
 12. The method of claim 10,wherein the WDM multiplexing/de-multiplexing system further comprises anoptical receiving device to function or work with said lens array,wherein said optical receiving device comprises (i) the plurality ofoptical detectors, configured to receive said first light beams fromsaid lens array and (ii) a first electrical circuit comprising theplurality of transimpedance amplifiers to function or work with saidoptical receiving portion.
 13. The method of claim 12, wherein saidoptical receiving portion comprises an optical detector array.
 14. Themethod of claim 10, wherein the WDM multiplexing/de-multiplexing systemfurther comprises an optical transmitting device to function or workwith said lens array, wherein said optical transmitting device comprises(i) the plurality of optical transmitters, configured to emit saidsecond light beams through said lens array and (ii) a second electricalcircuit to function or work with said optical transmitters.
 15. Themethod of claim 14, wherein the optical transmitting portion comprises asurface emitting laser array or an edge-emitting laser array.
 16. Themethod of claim 10, wherein the WDM multiplexing/de-multiplexing systemfurther comprises the plurality of optical transmitters and theplurality of optical detectors, the optical transmitters beingconfigured to emit said second light beams through said lens array, andthe plurality of optical detectors being configured to receive saidfirst light beams through said lens array.
 17. The method of claim 16,wherein said optical receiving portion comprises an optical detectorarray, and said optical transmitting portion comprises a surfaceemitting laser array or an edge-emitting laser array.
 18. The system ofclaim 1, wherein said electrical metal lines or traces are completelybetween the transimpedance amplifiers and the interface for theelectrical cable or the host device.
 19. An opticaltransmitting-receiving device, comprising the WDMmultiplexing/de-multiplexing system of claim 1 and an opticaltransmitting portion, the optical transmitting portion comprising theplurality of optical transmitters.
 20. The opticaltransmitting-receiving device of claim 19, wherein the plurality ofoptical transmitters comprises a surface emitting or edge-emitting laserarray.
 21. A WDM de-multiplexing system, comprising: a de-multiplexerconfigured to separate and guide first light beams from an incident rayhaving a plurality of wavelengths to corresponding lenses on an opticaldevice; a lens array comprising said corresponding lenses to receivesaid first light beams from said de-multiplexer, wherein said lens arraycomprises four lenses in a row, oriented along a direction that isparallel with a back end of the optical device and perpendicular to saidfirst light beams; alignment holes accompanying or adjacent to said lensarray; a light-beam collimator configured to provide the first lightbeams directly to said de-multiplexer; and a printed circuit boardhaving a plurality of optical detectors oriented along the directionthat is parallel with the back end of the optical device, a plurality oftransimpedance amplifiers oriented along a direction that is parallelwith the plurality of optical detectors, an interface for an electricalcable or to a host device, and a plurality of electrical metal lines ortraces thereon, wherein the optical detectors comprise four opticaldetectors in a row, are compatible with the lens array, and receive thefirst light beams from the lens array, the electrical metal lines ortraces transmit an output from the transimpedance amplifiers to theinterface, and the transimpedance amplifiers are physically locatedbetween the optical detectors and the interface.
 22. The system of claim21, wherein said optical device comprises a plastic optical devicehaving said lens array, said de-multiplexer, and said light-beamcollimator thereon.
 23. The system of claim 22, wherein said lens arrayis integrated into said plastic optical device.
 24. The system of claim23, wherein said lenses are spaced apart by equal intervals.
 25. Thesystem of claim 22, wherein said plastic optical device comprises aninjection molded optical device.
 26. The system of claim 22, whereinsaid alignment holes are between said lens array and a peripheral edgeof said plastic optical device that is parallel to the back end of theplastic optical device.
 27. The system of claim 26, further comprising afiber patchcord or a cable having alignment pins corresponding to saidalignment holes.
 28. The system of claim 21, further comprising amultiplexer configured to combine and guide second light beams from aplurality of optical transmitters, the second light beams having aplurality of wavelengths and passing through said corresponding lenseson said optical device, wherein said multiplexer and said de-multiplexertogether form a bi-directional optical subassembly (BOSA).
 29. Thesystem of claim 28, wherein the second light beams received by thelight-beam collimator are collinear with the first light beams providedby the light-beam collimator.
 30. An optical receiving device,comprising the WDM demultiplexing system of claim 21 and an opticalreceiving portion, the optical receiving portion comprising theplurality of optical detectors and the plurality of transimpedanceamplifiers.